线程同步模型：
http://www.xue5.com/Developer/CSharp/755821_2.html
http://www.cftea.com/c/2012/03/5518.asp
http://www.cnblogs.com/aarond/p/AA.html
http://www.newxing.com/Tech/DotNet/jichu/SOCKET_370.html
